Various kinds of heat sinks (heat radiating fins) are used as heat radiating means in an electric product or an electronic apparatus such as a television, a computer, or a motor, an engine and a radiator of an automobile, various types of machinery, and the like for preventing malfunction or degradation of functions following heat radiation. As a constituent material of a heat radiating fin, a metallic material such as aluminum or copper having a high heat conductance is generally used.
As a method of improving a heat radiating effect of such a heat sink, various methods have been proposed up to now. For example, as a method of increasing a heat radiating area thereof, alumite work or blast work, and a method of increasing the number of fins (JP 11-238837 A), a method of curving an envelope of a heat radiating fin to increase velocity and flow rate of cooling wind passing through the heat radiating fin (JP 10-242357 A), a method of decreasing a heat capacity of a heat radiating fin (JP 10-116942 A), and the like have been adopted.
Moreover, in order to further improve the heat radiating effect, an air cooling system for cooling the air through ventilation with a combination of a heat radiating fin and a fan, a water cooling system using cooling water, and a cooling method using a Peltier element on a heat radiating fin side (JP 10-318624 A), and the like have been proposed.
All of the above-mentioned conventional cooling methods have various problems. For example, in the method of increasing the number of fins to increase a surface area of a heat radiating fin, if the number of fins is increased excessively, a flow of air is clogged, causing degradation in the heat radiating property. In addition, in the method of decreasing a heat capacity of a heat radiating fin, if the thickness of the fins is reduced excessively in order to reduce the heat capacity, mechanical strength decreases and the heat radiating fin is liable to be broken.
The alumite work or the blast work has a problem in that very small holes are clogged due to secular change, causing lowering of the heat radiating effect.
Although the above-mentioned air cooling system is simple in structure, since a heat conductance between the air and the fins is small, it is necessary to increase the heat radiating area or increase a flow rate of air using a fan. Thus, problems such as an increase in the size of an apparatus and noise following ventilation occur.
On the other hand, the water cooling system has a significant cooling effect because a specific heat of water is large and a heat conductance is high. However, the water cooling system requires a circulation system and a pump for circulating water and a radiator and a fan for radiating heat to the open air, and a structure thereof becomes complicated and an apparatus is enlarged. Accordingly, the cost and power consumption of the apparatus increases, which is economically disadvantageous.
Since the cooling method using a Peltier element requires a Peltier element, a heat radiating fin, and a fan, and power consumption of the Peltier element is large, the method is economically disadvantageous.